Not Applicable.
The present invention relates to methods and procedures for accessing and forming a bypass in a vessel or between vessels.
There are a great number of circulatory conditions requiring surgical intervention to place a graft either as a complete substitute for a dysfunctional vessel, a bypass about a stenotic portion of a vessel, or a replacement for a surgically removed portion of the vessel. For the most part, such vascular grafts are placed surgically, entailing surgical exposure of the native vessel at the junction sites, surgical arteriotomy or venotomy to open the vessel, and suturing of the graft material to the vessel or to tissue served by the vessel. A great number of prosthetic grafts have been developed to address problems such as the apportionment of flow at branching junctions, the matching of vessels of different sizes when such junction is necessary, and the fitting of vessels to a region of tissue such as the wall of a cardiac chamber, so as to establish a more or less natural blood flow.
In addition, recently a number of approaches have been proposed or developed for forming a junction with a natural vessel, or a bypass between points of one or more vessels, by percutaneous or interstitial access. For example, U.S. Pat. No. 5,443,497 of Venbrux and U.S. Pat. No. 5,755,775 of Trerotola et al. illustrate such devices wherein an acutely angled Y-junction or an expandable stent junction is inserted at a low angle to the side of a vessel and secured to form a connecting port or conduit. Percutaneous access and installation are effected, for example, by using a peel-away sheath to release the penetrating junction member, in a manner similar to that of various tunneling trocar placement procedures conventionally used for routing prosthetic vessels through muscle tissue. However, these approaches essentially create Y-junctions, using a structure analogous to a in-vessel stent to effect a seal along the remaining open portion of the vessel. This access geometry with a low angle of entry necessarily entails a long incision in the vessel side wall and requires an oblique and possibly traumatic access route through surrounding tissue for installation along a smoothly contoured path. The Y-geometry entrance may further partially obstruct a vessel or divert flow in an irregular or inappropriate manner.
Accordingly, it would be desirable to provide a method and system for percutaneous access to a blood vessel for establishing a graft bypass or shunt with the vessel.
It would further be desirable to provide such a system adaptable to diverse geometry, or adaptable to arterial bypass, arterial to veinous grafts for dialysis access, and veinous to veinous grafts for occlusions or stenosis.
It would also be desirable to provide such a system forming a true end-to-side anastomosis.
One or more of these desirable objects are achieved in accordance with the present invention by a prosthetic vessel graft having a tube of synthetic graft material surrounding a self expanding stent. The graft and stent are mounted on a stiff introducer member which may be tunneled through skin or inserted in an opening and pushed down to a vessel for introducing the graft through the side wall of a vessel. Preferably the introducer has a hollow core and is configured to follow a guide wire which may be initially inserted by conventional techniques up to and through an opening in the side wall of the vessel. A peel-away sheath covers the stent and graft, and the stent has a plurality of collapsible anchor members at its distal end in the form of wire-like arms or hooks which initially are held tightly against the circumference of the stent and which spring outwardly in a radial direction when released from the sheath. In use, the intravascular end of the graft is inserted through an opening in the side of the vessel and the sheath is removed to release the anchors and secure the graft as a pure end-to-side anastomosis to the vessel.
In a preferred practice of the invention, a basic graft unit consists of the prosthesis tube and anchoring stent within the tube at one end thereof. The other (extravascular) end of the graft tube may have a blood compatible fitting or connector, or may have a reinforced band or collar suitable for suturing or other surgical joining technique. Two such prostheses are employed in a bypass procedure, and one is installed as described above at each vessel access point of an intended shunt or bypass. The two extravascular ends and bodies of the respective prostheses are then tunneled through tissue to a common point at a proximal cut-down or opening. Each segment is then back-flushed with saline and the ends are joined to each other, by suturing or by a quick-connect fitting that is attached or preattached to each of the prostheses, thus connecting them into a single continuous bypass or shunt. The opening may then be closed.